Formation of a metallic pattern utilized for such as a circuit has been conventionally performed by a method utilizing a resist material.
That is, after a resist material is coated on a metallic foil layer, unnecessary resist being removed by a development after light exposure of a required pattern, metallic foil exposed being removed by etching, and further the remaining resist portion is peeled off, whereby metallic foil on which a metallic pattern has been recorded is formed.
However, in this method, because the process is manifold and consumes plenty of time, and there are many useless points with respect to manufacturing time and utilization efficiency of energy and starting materials such as due to removal of unnecessary resist and metallic foil, improvement has been required.
In recent years, noticed has been a method for forming a metallic pattern, such as described in JP-A 2002-299833 (hereinafter, JP-A refers to Japanese Patent Publication Open to Public Inspection No.), in which ink containing so-called metallic nano-particles is utilized and a metallic pattern is directly drawn by means of such as screen printing or inkjet printing.
This metallic pattern forming method is a method to form a circuit by sintering metallic nano-particles at approximately 200-300° C., utilizing that the melting point of metallic nano-particles is lowered by minimizing the particle size thereof.
This technology, although surely has an advantage of such as decreased processing steps and improvement of utilization efficiency of starting materials, there is remained a problem that complete fusing of metallic particles together was difficult and there were severe limitations of temperature and conditions in the post treatment to reduce the electric resistance of a metallic pattern after sintering.
Further, known is a method in which metal salt, without utilizing metallic nano-particles, is utilized to make a metal ion form in ink and a conductive pattern is formed from a solution containing a reducing agent having reducing power under heating.
However, there was a problem that, because ability of a complexing agent, which coordinates to metal salt and stabilizes said metal salt, was insufficient, a reducing reaction of metal salt easily proceeded resulting in poor storage stability of a solution.
On the other hand, proposed is a method in which a metallic pattern is formed utilizing nonelectric plating technology as a means to generate and precipitate metal under a mild condition.
For example, as described in JP-A 7-131135, known is a method in which a metallic pattern is formed by nonelectric plating after forming a circuit pattern by an inkjet method utilizing ink containing a catalyst which enables nonelectric plating.
Further, known is a method, in which a nonelectlic plating catalyst is adsorbed on the surface of a support, on which hydrophilic graft polymer chains are present, by means of such as an inkjet method and said surface is subjected to nonelectric plating, whereby a conductive pattern excellent in resolution, conductivity and durability is prepared (JP-A 2007-42683).
Further, as ink utilized in the above-described inkjet method, for example, ink containing palladium metal salt as a precursor of a nonelectric plating catalyst is utilized. This ink is printed to form a pattern, which is further subjected to nonelectric plating, whereby a metallic pattern is formed.
However, even in these methods, there were problems that reproducibility of fine lines is insufficient, adhesion between a metallic pattern and a substrate may be insufficient, and production efficiency is not satisfactory because an additional layer should be provided on a support.